EnhancedSwitch

An enhanced switch, similar to Java.

This library targets Node.js 16, 18 and 20, but can also work in the browser.

Installation

npm i enhanced-switch

Usage

TypeScript

import EnhancedSwitch from "enhanced-switch";

const value = 2;

new EnhancedSwitch(value)
    .case(1, () => console.log("one"))
    .case(2, () => console.log("two"))
    .default(() => console.log("default"));

const result = new EnhancedSwitch<number, string>(value)
    .case(1, () => "one")
    .case(2, () => "two")
    .default(() => "default").value;

JavaScript

import EnhancedSwitch from "enhanced-switch";

const value = 2;

new EnhancedSwitch(value)
    .case(1, () => console.log("one"))
    .case(2, () => console.log("two"))
    .default(() => console.log("default"));

const result = new EnhancedSwitch(value)
    .case(1, () => "one")
    .case(2, () => "two")
    .default(() => "default").value;

Documentation

Table of Contents

• Class EnhancedSwitch<T, U>
  • new EnhancedSwitch(expression: T)
  • enhancedSwitch.allowFallthrough
  • enhancedSwitch.break()
  • enhancedSwitch.case(valueN: T | T[], code: U)
  • enhancedSwitch.case(valueN: T | T[], code: (s: EnhancedSwitch<T, U>) => U | void)
  • enhancedSwitch.default(code: U)
  • enhancedSwitch.default(code: (s: EnhancedSwitch<T, U>) => U | void)
  • enhancedSwitch.default(code: U, returnvalueN: true)
  • enhancedSwitch.default(code: (s: EnhancedSwitch<T, U>) => U | void, returnvalueN: true)
  • enhancedSwitch.expression
  • enhancedSwitch.hasConcluded
  • enhancedSwitch.value

Class EnhancedSwitch<T, U>

The EnhancedSwitch evaluates an expression, matching the expression's value against a series of case clauses, and executes the statements after the first case clause with a matching value. The default clause of an EnhancedSwitch will be jumped to if no case matches the expression's value.

Template parameter	Description
T	Switch expression type
U	Switch return type

new EnhancedSwitch(expression: T)

Create a new EnhancedSwitch

Parameter	Type	Description
expression	T	An expression whose result is matched against each case clause.

enhancedSwitch.allowFallthrough

Whether to allow fallthrough. If true, the switch will continue to execute case clauses after the first match until a break is encountered. Defaults to false.

Type: boolean. Read-only.

enhancedSwitch.break()

Prevent further execution of any subsequent case or default clauses.

Returns: this (EnhancedSwitch<T, U>)

enhancedSwitch.case(valueN: T | T[], code: U)

A case clause used to match against expression. If the expression matches the specified valueN (which can be any expression), this case clause is executed.

Parameter	Type	Description
valueN	T	The case clause is executed if the expression matches this value, or at least one value if this is an array.
code	U	The value to return if the case matches.

Returns: this (EnhancedSwitch<T, U>)

enhancedSwitch.case(valueN: T | T[], code: (s: EnhancedSwitch<T, U>) => U | void)

A case clause used to match against expression. If the expression matches the specified valueN (which can be any expression), this case clause is executed.

Parameter	Type	Description
valueN	T	The case clause is executed if the expression matches this value, or at least one value if this is an array.
code	(s: EnhancedSwitch<T, U>) => U | void	The function to run if the case matches.

Returns: this (EnhancedSwitch<T, U>)

enhancedSwitch.default(code: U)

A default clause; if provided, this clause is executed if the value of expression does not match any of the case clauses. An EnhancedSwitch can only have one default clause.

Parameter	Type	Description
code	U	The value to return if no case matches.

Returns: this (EnhancedSwitch<T, U>)

enhancedSwitch.default(code: (s: EnhancedSwitch<T, U>) => U | void)

A default clause; if provided, this clause is executed if the value of expression does not match any of the case clauses. An EnhancedSwitch can only have one default clause.

Parameter	Type	Description
code	(s: EnhancedSwitch<T, U>) => U | void	The function to run if no case matches.

Returns: this (EnhancedSwitch<T, U>)

enhancedSwitch.default(code: U, returnvalueN: true)

A default clause; if provided, this clause is executed if the value of expression does not match any of the case clauses. An EnhancedSwitch can only have one default clause.

Parameter	Type	Description
code	U	The value to return if no case matches.
returnvalueN	true	If true, the provided value is returned instead of the switch instance.

Returns: U

enhancedSwitch.default(code: (s: EnhancedSwitch<T, U>) => U | void, returnvalueN: true)

A default clause; if provided, this clause is executed if the value of expression does not match any of the case clauses. An EnhancedSwitch can only have one default clause.

Parameter	Type	Description
code	(s: EnhancedSwitch<T, U>) => U | void	The function to run if no case matches.
returnvalueN	true	If true, the provided value is returned instead of the switch instance.

Returns: U

enhancedSwitch.expression

An expression whose result is matched against each case clause.

Type: T. Read-only.

enhancedSwitch.hasConcluded

Whether the switch statement has concluded (no further case or default will be executed). A switch can be concluded by calling enhancedSwitch.break() or constructing with allowFallthrough set to false.

Type: boolean. Read-only.

enhancedSwitch.value

The result of the switch statement.

Throws	When
TypeError	If the switch statement has no result, e.g. there is no default clause and no case clause matches the expression or returns a value.

Type: U. Read-only.